UCC2891x High-Voltage Flyback Switcher

Texas Instruments UCC2891x High-Voltage Flyback Switcher is dedicated to isolated flyback power supplies and provides output voltage and current regulation without the use of an optical coupler. The device incorporates a 700V power FET and a controller that processes operating information from the auxiliary flyback winding and from the power FET to provide precise output voltage and current control. The integrated high-voltage current source for a startup that is switched off during device operation and the controller current consumption that is dynamically adjusted allows very low standby power. Control algorithms in the Texas Instruments UCC2891x, combining switching frequency and peak primary current modulation, allow operating efficiencies to meet or exceed applicable standards. Discontinuous conduction mode (DCM) with valley switching is used to reduce switching losses. The maximum switching frequency is 115kHz. Protection features help to keep secondary and primary component stress levels in check across the operating range.